1. Technical Field
Aspects of the present invention relate to a sheet supplying device used for various types of image forming devices such as a facsimile device, a printer and a copying device.
2. Description of Related Art
Sheet supplying devices are widely used in various types of image forming devices. FIGS. 9A and 9B show a facsimile device 80 employing a conventional sheet supplying device. FIG. 9A is a side view of the sheet supplying device of the facsimile device 80, and FIG. 9B is an enlarged view of a circled portion D of the sheet supplying device shown in FIG. 9A. The facsimile device 80 is configured such that a plurality of sheets 84 stacked on a sheet tray 82 are supplied one by one to the inside of the facsimile device 80 by rotation (in counterclockwise direction in FIG. 9A) of a separation roller 86.
The sheets 84 are placed on the sheet tray 82 in a slanting position with the front edges thereof contacting with contact surfaces 88. A separation pad 90 is located at a lower left position of the separation roller 86 on FIG. 9A. The separation pad is attached to a holder 92. The holder 92 is configured to be capable of pivoting around its right side position so that the separation pad 90 closely contacts the separation roller 86 by a pressing force caused by a coil spring 94. The sheets 84 are separated one by one when being sandwiched between the separation roller 86 and the separation pad 90.
The contact surfaces 88 are located at a plurality of positions, along a sheet width direction, including both side positions of the separation roller 86 and both end positions of the sheet tray 82. Each contact surface 88 is a surface of a small rib-like member. When a sheet from sheet 84 is carried to a printing head 96, ink is transferred from an ink ribbon 98 to the sheet 84 to form an image on the sheet from sheet 84.
Japanese Patent Provisional Publication No. 2002-137838 discloses a conventional sheet supplying device employing a separation pad for removing sheets one by one.
As shown in FIG. 9B, in the conventional facsimile device 80, the contact surface 88 is inclined with respect to a mounting surface (which is usually a horizontal surface) by an angle β. Therefore, it is required to press the sheets 84 in a direction E by use of a pressing plate 89 for supplying the sheets toward the inside of the facsimile device 80.
FIGS. 10A to 10D show another type of a contact surface configured to eliminate the need for using the pressing plate 89. If the separation roller 86 starts to rotate (see FIG. 10A), a plurality of sheets are carried to the separation pad 90 (see FIG. 10B), and the plurality of sheets slide and are sandwiched between the separation roller 86 and the separation pad 90, so that the plurality of sheets press the separation pad 90 downward (see FIG. 10C). Consequently, a gap is formed between the separation roller 86 and the separation pad 90, by which a separating operation of the sheet supplying device is performed and a phenomenon that a plurality of sheets are carried into the inside of the facsimile device simultaneously may be occur (see FIG. 10D).